Electronics > FPGA

Help with Altera Cyclone III configuration problems.

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I've tried to make a development board for the Cyclone III, most of it works as far as I can tell without the FPGA.

My problem is with the FPGA configuring after I have successfully downloaded the configuration file to the serial memory. Referencing this document:


I can tell what stage the FPGA is in when powering up. Well nothing happens. The FPGA just sits there with NCONFIG at 1.5V, CONFIG_DONE at 0V and NSTATUS at 0V.

I think there may be something wrong with the FPGA as NCONFIG isn't at 0V, when I pull it low to reset the device and attempt to restart the configuration it drops a little to 1.2V.

I have gone over the pins and connection scheme and unfortunately haven't found any problems!

Attached is my schematic, it has some errors but I have made a rev1.1 schematic and changed those. One of those is the schematic says I'm using 1MB of memory when I'm using 16MB. I show rev1.0 as this is the revision of the board I'm working on.

Thanks for any help!

NCE is pulled low by 10k. I think it has internal 10k pull-up. Pull that hard to GND with 0Ohm.

Thanks for your reply. It is pulled low in the schematic however I replaced the 10k with 0R and no change.

I decided to test whether the pad on the bottom had continuity to GND and it didn't so I fixed that and the FPGA configures from the memory however now Quartus Programmer does not recognise the memory when the pad is connected to GND. It works when I lift it.

Can you program the FPGA using JTAG? Does CONF_DONE go up then?

Unfortunately I didn't bring the JTAG out and I can't mod it. :(

Do you have any other ideas?

I haven't had time to look at it since I got it working a bit. I have time tonight and see if I can solve it.


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